iPhone: Push or multitasking, what's the difference?

The 3rd party Push notifications have been announced two years ago, and are finally available for general use in iPhone OS 3. Apple has put up push notifications as an alternative to multitasking, mainly because multi-tasking apps running in the background would drain your battery quicker and multi-tasking would use more memory. 

Well, it is a fact that the more apps you are running simultanious, the more memory is used. And yes, especially if an application is polling the network for new messages, that can consume battery life quite quickly.
 
So, push notifications is the solution and holy grail for iPhone users.
 
Now, back into real life. I installed Worldvoice, a "radio" application that uses push for notifications of new "broadcasts" and such. So I switched on the push notifications and played around with the application a bit. I then switched the app off and pretty soon, a push message was shown. Cool. I got bored with it, and switched off the individual notification settings for Worldvoice. The general Push setting remained "on" (because I forgot about it) - see screenshot.

After half a day, I noticed that my iphone battery indicator dropped significantly more than I am used to.
 
Did some more tests during a few days and yes, even though you're not actually receiving any push notifications, just having the push notification enabled makes that your battery drains quite a bit quicker than usual. Because the connection to the push server and phone is open constantly.
 
I am now wondering if this push is actually such a good idea. It drains battery, even without using it. This is with only one app, with very few updates. If you have three or four apps, with a lot of updates (say a twitter client with notifications for DMs and Mentions, and an MSN client with notifications for messages, etc), I think your battery will be gone after a few hours. That sucks, and I think is not much different than just run the apps in the background, really.

Do more people have the above experience (or not?) and willing to share their opinion?

1 response
Other than not actually running in the background, there's 2 main differences from background apps:

1. The Apple Push Notification Service (APNs) keeps a persistent connection for each device that has pushed turned on. No matter how many applications you have that has pushed turn on, it should not use (much, at least) additional power other than keeping the single connection active. That said, I haven't experience that battery life is badly affected yet. I have seen some instability though.

I'm also thinking, typically if you use 3G, and if you move around quite a bit while a connection is active, it consumes much more power, I'm doubting if it is really a persistent connection. In reality, it's probably some kind of polling service even though it's documented as the former.

2. It doesn't require as much memory as background apps. Personally, this is an even bigger reason for me to prefer push to background apps.